The heart is a hollow muscular organ that contracts approx. 100,000 times a day and pumps approx. five liters of blood into the circulation every minute. It is not only characterized by the unique features of muscle tissue specialized to meet the constant physical demands of pumping blood, but also by muscle cells that send spontaneous rhythmic electrical impulses to stimulate contraction. This article gives an overview of the structure of the heart wall and of cardiac muscle tissue.

00:02
In this lecture, you are going to learn about
the histological structure of the heart.
00:09
Hopefully at the end of this lecture, you’ll have
a very good understanding of what endotheliumis. That you’ll understand the structure of
the heart and how blood flows through theheart. And how the pumping of the heart is
controlled by the impulse conducting system,and how Purkinje fibres are able to distribute
impulses through the heart muscle.
00:38
It’s important that you understand the difference
between Purkinje fibres which are normal cardiacmuscle fibres but specialized for conduction,
how to distinguish those fibres from cardiacmuscle that specialize to pump, to contract,
and move blood through the heart. It’s alsoimportant you understand the difference
between the structure of cardiac muscle andsmooth muscle and skeletal muscle. Now, it’s very,
very important that you understand endothelium.
01:17
Endothelium has an enormous number of functions
throughout the body. And each of these functionswill be dealt with in more detail in other
parts of the body systems. But endotheliumforms a very thin lining of all the blood
vessels in our body. It has a very importantfunction of being a barrier, and only allowing
certain substances to pass across the wallof this very, very small thin epithelial lining
of all blood vessels. Of course, the heartis structured in such a way that it’s able
to pump blood, first of all, to the lungsto be oxygenated, to then receive that blood
back and pump that oxygenated blood to therest of the body. So the structure of the
heart is a very important concept structureto understand. It’s also very important to
understand the sequence of blood flow throughthe heart because as I said a moment ago,
the heart is structured in such a way thatthe sequence of blood flow through the heart
is highly coordinated. And without that propersequence of blood flow from the heart, then
we would not have the ability to oxygenateour blood and to carry oxygenated blood to
the rest of the body. First of all, let’sexplain or let’s clearly understand what
we mean by the term endothelium.
02:53
Endothelium is a very special name given to the
epithelial lining throughout the cardiovascular system.
02:59
It’s the thin epithelium that is in contact
with the lumen of the blood vessels and eventhe lumen of the heart, that consists of a
very flattened squamous epithelial cell.
03:15
And they’re also very tightly bound to each
other because one of the jobs of endotheliumis to be a selective barrier for transport
across the epithelial surface. But endothelialcells also have an enormous number of other
functions. Some of those functions I’velisted on the left-hand side of this slide.
And I’ll refer to these functions in laterlectures when I deal with their function in
different organ systems.

About the Lecture

The lecture Heart: Introduction by Geoffrey Meyer, PhD is from the course Cardiovascular Histology.

Included Quiz Questions

Which ONE of the following statements about "endothelium" is NOT CORRECT?

Consists of epithelial cells loosely bound to each other forming a very permeable layer between the lumen of blood vessels and surrounding tissue.

Forms the epithelium lining of all blood vessels and the heart.

Is a flattened (squamous) layer of epithelial cells.

Is a very important selective barrier between the blood and cells/tissues of the body.

Is immediately adjacent to the blood.

Which of the following statements regarding endothelium is CORRECT?

It affects the contraction and relaxation of smooth muscles in the tunica media.

It is highly permeable.

It has thrombogenic barrier.

It has no effect on vascular resistance.

It has cuboidal type of epithelium.

Author of lecture Heart: Introduction

Geoffrey Meyer, PhD

Customer reviews

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It is really fascinating with the clarity that is expressed and the rhythm as it goes, if the proper attention and reason is giv

By Luis E. on 15. March 2019 for Heart: Introduction

It is really fascinating with the clarity that is expressed and the rhythm as it goes, if the proper attention and reason is given, the presentation is totally understandable

clear and concise

By Romaine B. on 31. August 2018 for Heart: Introduction

clear intro, to the point and simple to understand, very simple

Rubbish

By UWA S. on 08. August 2017 for Heart: Introduction

This is very unclear and annoying, everything is everywhere and is hard to figure out what we need to do

User Reviews

(3)
3,7 of 5 stars

5 Stars

2

4 Stars

0

3 Stars

0

2 Stars

0

1 Star

1

It is really fascinating with the clarity that is expressed and the rhythm as it goes, if the proper attention and reason is giv

By Luis E. on 15. March 2019 for Heart: Introduction

It is really fascinating with the clarity that is expressed and the rhythm as it goes, if the proper attention and reason is given, the presentation is totally understandable

clear and concise

By Romaine B. on 31. August 2018 for Heart: Introduction

clear intro, to the point and simple to understand, very simple

Rubbish

By UWA S. on 08. August 2017 for Heart: Introduction

This is very unclear and annoying, everything is everywhere and is hard to figure out what we need to do

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